<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>HTML和CSS示例</title>
    <link href="test.css" type="text/css" rel="stylesheet" />
</head>
<body>
    <h1>我是个一级标题</h1>
    <div class="note">我是一个note DIV（层）</div>
    <div class="nav">我是一个nav DIV(层）</div>
    <div class="note">我是另一个note DIV（层）</div>
</body>
</html>